A total of about 300 peptides were supplied to laboratories within the NIAID. This tabulation does not take into account the length of the peptides, additional functional groups such as the addition of phosphate, biotinyl and fluoresceinyl groups, chemical modifications, or the amount requested with is quite variable. As examples in LMS peptides have been utilized for detailed studies on peptide binding to major histocompatibility complex class I molecules in order to determine how this complex interacts with T cell receptors on cytotoxic T lymphocytes, to verify the nature of endogenous peptides isolated from class I proteins and to examine the specificity of NK receptors. Other peptides have been used to prepare antisera to the alpha and beta chains of integrins and to act as natural ligands for integrins in order to study lymphocyte activation, interaction, and trafficking; and to make antibodies for proteins identified by gene cloning techniques.